textproduct: Quad Cities

KEY MESSAGES

- Wildfire smoke to create hazy skies and poor air quality through Monday.

- Strong to severe storms are possible Monday and Monday night with potentially two rounds occurring. The Storm Prediction Center has an enhanced, level 3 out of 5, risk of severe storms along/north of I- 80. South of I-80 a slight, level 2 out of 5, risk for severe storms exist.

- Hot and humid conditions are expected area-wide on Monday. A Heat Advisory has been issued for portions of the area, to the west and southwest of the Quad Cities, for peak heat indices up to 105 degrees.

SHORT TERM /THROUGH TONIGHT/

Issued at 236 PM CDT Sun Jul 19 2026

If you've been outside today in eastern Iowa or northwest Illinois, you likely noticed the smoke that moved in last night. Near surface smoke and concentrations aloft are expected to remain hazardous for sensitive groups through much of Monday before moving out with a cold front, prompting Air Quality Alerts for eastern Iowa and northwest Illinois from state partners. Any rain overnight and Monday will also help decrease the concentrations in the air, though the greatest uncertainty is when that rain will occur.

The story for tonight through Monday continues to be focused around a potent shortwave descending across the Great Lakes region. Kinematics will be favorable for organized thunderstorms given shear in excess of 50 kts and ample instability. This combination is slightly unusual, as shown by EFI CAPE-shear values near the 75th percentile. With this favorable environment, the primary question is when will storms occur. Early Monday morning (likely by 6-7 AM), a decaying cluster of showers and storms is expected to move into eastern Iowa and northwest Illinois, keeping north of Interstate 80. However, there are two points of uncertainty with these early morning storms: first, whether they decay before or after they reach the area, and secondly, if they do reach eastern Iowa, how long do these storms persist through the morning. The most likely scenario is that these storms decay by noon, which will allow for peak diurnal heating to occur.

Following Monday's morning round of storms, surface heating and a moist boundary layer will amplify both the instability and heat indices. This effect will be especially pronounced in areas south of Interstate 80 and west of Interstate 380, as a longer period of diurnal heating will allow for heat indices to reach over 100 degrees. A Heat Advisory is in effect for these areas for Monday afternoon and evening, and may need to be expanded if morning storms do not evolve as expected.

The greatest concern for Monday, in addition to early morning storms and heat headlines, is the chance for severe storms Monday evening into overnight ahead of a cold front. High shear and instability, coupled with dynamic forcings, will allow for scattered to numerous severe storms to develop. How these storms play out are presented in the following scenarios, which reflect differences in the evolution of morning storms and where and when afternoon storms form:

Scenario 1: Morning storms decay by mid to late morning, leaving behind boundaries and allowing for destabilization during the afternoon. Storms initiate across northeast Iowa into southwest Wisconsin around early evening and move southeastward at 35+ mph. These storms would be capable of all severe threats, including tornadoes. Upscale growth would then result in a line of storms with the potential for fast-moving bowing segments. The primary hazard with these storms would be damaging winds with localized significant gusts (> 75 mph) and brief spin-up tornadoes. This scenario would keep the greatest severe threat from 6 PM to 12 AM.

Scenario 2: Scenario 2 follows the same evolution of morning storms as Scenario 1, with the main difference being the location of storm initiation. In this scenario, storms initiate further upstream across southeastern Minnesota and western Wisconsin by early evening. This would limit the all-hazards severe threat due to the rapid upscale growth, allowing instead for a mature linear system with bowing segments. Damaging winds with localized significant gusts (> 75 mph) and brief spin-up tornadoes would be the primary threat. This would also result in the storms arriving later, pushing the greatest severe threat to 8 PM to 2 AM.

With both of these scenarios, heavy rain will be possible, with guidance showing PWATs near or greater than 2.0 inches. Due to moderate storm motions and limited rainfall over the past several days, flash flooding concerns are low, though any areas that have extended periods of rain may be at a low risk of ponding. Additional showers and sub-severe storms will be possible behind the line of storms through early Tuesday morning.

LONG TERM /MONDAY THROUGH SUNDAY/

Issued at 236 PM CDT Sun Jul 19 2026

Tuesday through Thursday Assessment...a certainty (>98%) of cooler and much less humid conditions after Tuesday

Tuesday will be dry as high pressure builds into the Midwest and the flow aloft turns to the northwest. Heat indices will range from the mid 80s to the low 90s due to lingering humidity until dew points drop Tuesday night.

Wednesday through Thursday look to be banner days; daytime highs 80 to 85 and low humidity levels.

Thursday night through Friday night Assessment...low (<25%) confidence regarding rain chances

Late Thursday night through Friday evening an upper level respectable upper level disturbance in the northwest flow will be paired with a weak surface low moving through Missouri.

The model consensus has 20-30% chances for rain centered mainly around late Thursday night and Friday morning. Given the northwest flow aloft across the area, moisture will be limited so it raises questions on how much rain could occur and what the real areal coverage of it will be.

The better moisture will run from the Plains into Missouri and there will be a frontal boundary associated with the low as it moves from Kansas across Missouri. I suspect the better rain chances will be along the frontal boundary across Missouri.

Saturday and Sunday Assessment...a certainty (>95%) of humidity levels starting to rise

Return flow begins on Saturday as the heat dome builds north in the Plains. While not the overly humid conditions earlier in the week, dew points will start climbing into the low to mid 60s as temperatures climb above normal again.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 617 PM CDT Sun Jul 19 2026

Hazy/smoky skies to continue to bring MVFR/brief IFR vsbys to the terminals this evening, persisting the longest at CID/DBQ tonight. Near surface smoke output from latest model solutions and current observations suggest that MVFR vsbys may even persist through mid-morning Monday, especially along and east of MS RVR. Will continue to monitor trends for any updates/amendments this evening. A lead shortwave to move across southern MN early Monday, bringing a risk of showers/storms late morning/early afternoon. However, confidence in areal extent and timing remains low and have only included PROB30 mention at DBQ at this time. Additional showers and storms will be possible late in the period and just beyond that may become strong to severe, with gusty winds and heavy rain. Confidence in overall coverage and timing too low to include mention with the 00z TAFs.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Heat Advisory from noon to 8 PM CDT Monday for IAZ051-063- 076>078-087>089-098-099. IL...Heat Advisory from noon to 8 PM CDT Monday for ILZ025-034. Air Quality Alert until midnight CDT Monday night for ILZ001- 002-007-009-015>018-024>026-034-035. MO...Heat Advisory from noon to 8 PM CDT Monday for MOZ009-010.